1. Field of the Invention
The present invention relates to an organic light-emitting display device, and more particularly to an organic light-emitting display device characterized by improved brightness and reduced power consumption.
2. Description of the Related Art
An organic light-emitting display device is a self-emission display for displaying an image by using an organic light-emitting diode (OLED). Light is emitted by energy that is generated when an exciton drops from an excitation state to a ground state within an organic emissive layer where the organic light-emitting display device displays an image.
The organic light-emitting display device may be classified into a bottom-emission type and a top-emission type. The organic light-emitting display device forms cathode electrodes as common electrodes on entire pixel areas. In the case of the bottom-emission type, the cathode electrodes function as a reflective layer. Accordingly, the cathode electrodes may be formed of thick and low-resistance material in order to minimize an internal-resistance (IR) drop of the common voltage ELVSS in the cathode electrodes. Meanwhile, with regard to the top-emission type, the cathode electrodes function as a transmissive layer and are formed of thin and transparent materials along with low electrical resistivity in order to increase light transmission. Therefore, a voltage drop increases in the cathode electrodes due to high resistance. Specifically, when a size of the display device increases, a voltage drop in the cathode electrodes increases, which causes unevenness in image quality and characteristics.
Therefore, it is necessary to utilize an advantage of the top-emission type and minimize a voltage drop in the cathode electrodes.